1. Field of the Technology
The present application relates generally to wireless communication networks and devices, such as IEEE 802.11-compliant wireless local area networks (WLANs) and devices.
2. Description of the Related Art
Institute of Electrical and Electronics Engineers (IEEE) 802.11 Wireless Local Area Network (WLAN) compliant devices, such as 802.11a, 802.11b, 802.11g, dual-band, etc. devices, are becoming increasingly popular. Such IEEE 802.11-based WLANs are undergoing a massive deployment which will continue throughout the next decade. Locations that offer 802.11 WLAN connectivity are often referred to as “hotspots,” where access points (APs) are utilized to provide wireless connections with mobile communication devices.
In these environments, Extended Service Set (ESS) mesh networking may provide the AP interconnection needed to backhaul traffic in and out of these hotspots and perform mesh-like traffic relaying. Solar and battery-powered wireless APs are becoming a reality in these environments as well. Thus, an 802.11 WLAN solution which accommodates ESS mesh networks and is applicable to battery-powered APs, such as those which operate under solar power, would be useful.
Some additional background and discussion regarding such wireless technologies are provided in the following publications: [1] T. Adachi and M. Nakagawa, “Capacity Analysis For A Hybrid Indoor Mobile Communication System Using Cellular and Adhoc Modes,” The 11th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'2000), volume 2, pages 767-771, 2000; [2] X. Wu, S H. G. Chan, and B. Mukherjee. Madf, “A Novel Approach To Add An Adhoc Overlay On A Fixed Cellular Infrastructure,” IEEE Wireless Communications and Networking Conference (WCNC'2000), volume 2, pages 549-554, 2000; [3] C. Qiao and H. Wu. Icar, “An Integrated Cellular And Adhoc Relay System,” Ninth International Conference on Computer Communications and Networks, pages 154-161, 2000; [4] Y D. Lin and Y C. Hsu, “Multihop Cellular: A New Architecture For Wireless Communications,” IEEE INFOCOM 2000, volume 3, pages 1273-1282, 2000; [5] B. S. Manoj R. Ananthapadmanabha and C. S. R Murthy, “Multihop Cellular Networks: The Architecture And Routing Protocols,” 12th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, volume 2, pages G78-G82, 2001; [6] T. Rouse, I. Band, and S. McLaughlin, “Capacity And Power Investigation Of Opportunity Driver Multiple Access (ODMA) Networks In TDD-CDMA Based Systems,” IEEE International Conference on Communications, 2002; [7] G. N. Aggelou and R. Tafazolli, “On The Relaying Capability Of Next Generation GSM Cellular Networks,” IEEE Personal Communications, pages 40-47, February 2001; [8] M. J. Miller, W. D. List, and N. H. Vaidya, “A Hybrid Network Implementation To Extend Infrastructure Reach,” Technical report, University of Illinois, January 2003; [9] R. S. Chang, W. Y. Chen, and Y. F. Wen, “Hybrid Wireless Network Protocols,” IEEE Transactions on Vehicular Technology, 52(4):1099-1109, July 2003; [10] J. H. Yap, X. Yang, S. GhaheriNiri, and R. Tafazolli, “Position Assisted Relaying And Handover In Hybrid Ad Hoc WCDMA Cellular System,” 13th IEEE International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC'2002), Lisbon, Portugal., pages 2194-2198, September 2002; [11] Y D. Lin, Y C Hsu, K W. Oyang, T C. Tsai, and D S. Yang. “Multihop Wireless IEEE 802.11 LANs: A Prototype Implementation,” IEEE International Conference on Communications (ICC'99), volume 3, pages 1568-1572, 1999; and [12] IEEE Standards Department, IEEE Draft Standard Wireless LAN. IEEE Press, 1996.
The state of the art reflects much activity that considers the inclusion of multihop relaying into wireless infrastructure networks. A variety of systems have been considered, and these systems often differ on the basis of whether the mobiles have multiple air interfaces, whether multihop infrastructure is present, and whether WLAN and/or cellular is being considered. See generally documents [1], [2], [3], [4], [5], [6], [7], and [8]. The system defined in document [1] uses multihop networking to enable communications whenever nodes are within range without use of the cellular infrastructure. This is also the objective in document [9] but, to maintain simplicity, a maximum of two ad hoc hops may be used between the end stations. In mobile assisted data forwarding (MADF) in document [2], special forwarding channels are allocated from resources used by the existing cellular network. These channels are then used for relaying traffic between cells. The approach in ICAR of document [3] is similar to this approach, but utilizes special preinstalled multihop relay stations to move traffic between cells. The multihop cellular system incorporates multihop relaying into the cellular network using the same air interface as that used by the cellular base stations (BSs) as in documents [4] and [5]. This concept is similar to the opportunity driven multiple access (ODMA) system proposed in document [6] and the system described in document [7]. In document [10], a mechanism referred to as “position assisted relaying” was proposed for WCDMA cellular networks with dual mode stations. In this scheme, a nearby station may relay transmissions for another when that station's cellular link becomes unusable. Finally, in document [8], a design is presented for achieving range extension using mobile station based multihop networking.
What are needed are techniques which may be used in IEEE 802.11 WLANs to enable wireless APs to reduce their power consumption (i.e. achieve improved power savings) and/or to perform multi-channel traffic relaying using a single radio interface.